Marta Kostyuk, a 15-year-old qualifier from Ukraine who beat 25th-seeded Peng Shuai in the first round, has advanced to the third round of the Australian Open, while second-seeded Caroline Wozniacki needed a miraculous comeback to stay alive.

Venus Williams, a finalist last year, is out of the Australian Open, beaten 6-3, 7-5 by Belinda Bencic on Monday. Her first-round exit followed that of US Open champion Sloane Stephens, who lost to Zhang Shuai despite serving for the match.